Global warming and changes in drought

• Published in: Nature climate change Vol. 4; no. 1; pp. 17 - 22
• Main Authors: Trenberth, Kevin E., Dai, Aiguo, van der Schrier, Gerard, Jones, Philip D., Barichivich, Jonathan, Briffa, Keith R., Sheffield, Justin
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-01-2014; Nature Publishing Group
• Subjects: 704/106/242; 704/106/35/823; 704/106/694/674; Climate Change; Climate Change/Climate Change Impacts; Climatology. Bioclimatology. Climate change; Continental interfaces, environment; Drought; Earth, ocean, space; El Nino; Environment; Environmental Law/Policy/Ecojustice; ENVIRONMENTAL SCIENCES; Evapotranspiration; Exact sciences and technology; External geophysics; GEOSCIENCES; Global warming; Hydrologic data; La Nina; Meteorology; Ocean, Atmosphere; perspective; Sciences of the Universe; Southern Oscillation; time series analysis; El Niño Southern Oscillation; atmospheric precipitation; climate warming; 1950-2000; climate variability; Climatic index; El Nino; drought; global change; 2000-2010; Natural hazards; uncertainties; climate change
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/nclimate2067

Recent studies have produced conflicting results about the impacts of climate change on drought. In this Perspective, a commonly used drought index and observational data are examined to identify the cause of these discrepancies. The authors indicate that improvements in the quality and coverage of precipitation data and quantification of natural variability are necessary to provide a better understanding of how drought is changing.
Several recently published studies have produced apparently conflicting results of how drought is changing under climate change. The reason is thought to lie in the formulation of the Palmer Drought Severity Index (PDSI) and the data sets used to determine the evapotranspiration component. Here, we make an assessment of the issues with the PDSI in which several other sources of discrepancy emerge, not least how precipitation has changed and is analysed. As well as an improvement in the precipitation data available, accurate attribution of the causes of drought requires accounting for natural variability, especially El Niño/Southern Oscillation effects, owing to the predilection for wetter land during La Niña events. Increased heating from global warming may not cause droughts but it is expected that when droughts occur they are likely to set in quicker and be more intense.